JP2008223152A - Sheet for civil engineering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet for civil engineering, containing a biomass-based polymer in at least a part of the sheet in contrast to the conventional civil engineering sheet comprising a knit fabric composed solely of a petroleum-based polymer or a biomass-based polymer, friendly to the environment and solving the problems of poor abrasion resistance, etc., of a biomass-based polymer compared with a petroleum-based polymer. <P>SOLUTION: The civil engineering sheet is formed by a three-dimensional knit fabric. At least 50 mass% of the fiber constituting the three-dimensional knit fabric is a conjugated fiber having a sheath-core cross-section, wherein the sheath part is made of a petroleum-based general-purpose polymer and the core part is made of a biomass-based polymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a civil engineering sheet formed by a three-dimensional knitted fabric composed of a composite fiber having a biomass-derived polymer as a core component, which is suitable for uses such as greening, drainage and erosion prevention, and has excellent wear resistance. It is related to the sheet.

  Most of the conventional synthetic fibers are made from limited fossil resources such as oil. However, these fossil resources are not only concerned about depletion in the future, but carbon dioxide generated during incineration and disposal is It is a big social problem as a causative substance. On the other hand, biomass-derived substances that originate from carbon dioxide in the atmosphere, even if incinerated, were originally in the atmosphere, so the mass volume of carbon dioxide does not increase macroscopically. . This idea is called “carbon neutral” and tends to be regarded as important. However, since the synthetic fiber derived from biomass is generally inferior to conventional general-purpose synthetic fibers in wear resistance, it is an obstacle to expanding applications.

  Therefore, in recent years, a hybrid material of a synthetic resin derived from biomass and a synthetic resin derived from petroleum has attracted attention as a material that supplements both of the above problems. As one example, for example, on the raw yarn surface, there is a composite yarn in which a polylactic acid resin is used for a core portion and an aromatic polyester resin is arranged in a sheath, which is disclosed in Patent Documents 1, 2, and 3 and the like. However, the prior literature does not give detailed descriptions of specific uses, and does not disclose required characteristics for each material.

  On the other hand, for civil engineering sheets, for example, in Patent Documents 4 and 5, the form and sewing method are disclosed, but they are formed from synthetic fibers made of general fossil resources and are environmentally friendly. is not. Therefore, a civil engineering sheet that is environmentally friendly and excellent in abrasion resistance has not yet been found.

JP 2004-353161 A JP 2005-187950 A JP 2005-232627 JP 05-187011 A JP-A-10-196296

  The present invention has been made in view of such a current situation, and is not a synthetic fiber composed only of conventional petroleum-derived polymers but contains biomass-derived polymers at least in part, and generates carbon dioxide at the time of incineration disposal An object of the present invention is to provide a civil engineering sheet that is environmentally friendly, such as reducing the amount, and that can compensate for defects such as abrasion resistance that are inferior to biomass-derived polymers compared to petroleum-derived polymers.

As a result of intensive studies to solve such problems, the present inventors have shown that the cross-sectional shape is a core-sheath shape, the sheath is a petroleum-based general-purpose polymer, and the core is a biomass-derived polymer. The present inventors have found the fact that a civil engineering sheet made of a knitted fabric composed of composite fibers formed has excellent wear resistance, and has reached the present invention.
That is, the gist of the present invention is as follows.
(A) A civil engineering sheet formed of a three-dimensional knitted fabric, wherein at least 50% by mass or more of the fibers constituting the three-dimensional knitted fabric have a core-sheath cross-section, and the sheath is a petroleum-based general-purpose A civil engineering sheet characterized by being a composite fiber formed of a polymer and having a core formed of a biomass-derived polymer.
(B) The civil engineering sheet according to (a), wherein the sheath is formed of polyethylene terephthalate.
(C) The civil engineering sheet according to (a) or (b), wherein the core is formed of polylactic acid.
(D) Any of (a) to (C), wherein the connecting yarn in the three-dimensional knitted fabric is a monofilament of 220 to 3330 dtex, the thickness of the sheet is 10 mm or more, and the mass is 500 to 3000 g / m ² . The civil engineering sheet described.
(E) The sheet for civil engineering according to any one of (a) to (d), wherein the heat-sealing yarn is used in an amount of 3 to 20% by mass.
(F) The civil engineering sheet according to any one of (a) to (e), which is processed with a resin at 1 to 100% omf.

  The civil engineering sheet of the present invention, unlike a civil engineering sheet consisting only of a conventional petroleum-derived polymer, preferably contains a biomass-derived polymer, and therefore can significantly reduce carbon dioxide emissions during incineration disposal. . In addition, the three-dimensional knitted fabric used in the present invention includes 50% by mass or more of core-sheath composite fiber having a structure in which a fiber derived from a biomass is coated with a petroleum-based polymer. This makes it possible to compensate for the disadvantage of inferior wear resistance unique to biomass-derived polymers. As a result, the civil engineering sheet of the present invention has a low environmental load and an excellent balance of application properties such as mechanical strength and wear resistance.

Hereinafter, the present invention will be described in detail.
The civil engineering sheet of the present invention needs to be formed of a three-dimensional knitted fabric. The three-dimensional knitted fabric in the present invention has a structure having an upper and lower structure, and the upper and lower structure is connected by a connecting yarn.

  Here, the connecting yarn is a monofilament, and its fineness is preferably 220 to 3330 dtex. When the fineness of the connecting yarn is less than 220 dtex, the three-dimensional shape may be difficult, or the connecting yarn will not be able to withstand the mass of earth and sand or fortification on the upper structure, and the connecting yarn will sleep and have no three-dimensional effect Or there may be insufficient strength in terms of wear resistance. On the other hand, when the connecting yarn has a fineness larger than 3330 dtex, the connecting yarn has a high rigidity, and therefore, the knitting structure with the upper and lower structures may be distorted, which may hinder the knitting property.

  The fibers constituting the upper and lower tissues are not particularly limited in shape, and may be monofilaments, multifilaments or spun yarns depending on the required properties, but considering shape retention and knitting properties. Then, it is desirable that it is a monofilament or multifilament having a fineness of 110 to 560 dtex.

  As the three-dimensional knitted fabric in the present invention, it is necessary that at least 50% by mass or more of the fibers constituting the knitted fabric is a composite fiber having a core-sheath cross-sectional structure, and the composite fiber is It is necessary that the sheath portion is a composite fiber formed of a general-purpose polyester derived from petroleum and the core portion formed of a bio-derived polymer.

  In the civil engineering sheet of the present invention, by using a polymer derived from biomass, it is possible to limit the release of carbon dioxide based on carbon that has been enclosed in fossil resources into the atmosphere, and a carbon neutral viewpoint. Can reduce the environmental impact. On the other hand, it has been pointed out that biomass-derived polymers are inferior in wear resistance to petroleum-based polymers that are representative of fossil resources, such as general-purpose polyesters. Therefore, in the civil engineering sheet of the present invention, since high mechanical properties are required, when using a biomass-derived polymer, a petroleum-based general-purpose polyester having high mechanical properties is arranged on the fiber surface, and the fiber It is necessary to be a core-sheath composite fiber in which a polymer derived from biomass is arranged.

  In the present invention, as a result of examining the balance between the environmental load reduction effect based on the use of a polymer derived from biomass and the mechanical properties required for a civil engineering sheet, the composite fiber having a core-sheath structure is 50% by mass in a three-dimensional knitted fabric. It became clear that this was necessary. That is, when the amount of the composite fiber used is less than 50% by mass, the mechanical properties of the civil engineering sheet are sufficient, but the content of biomass-derived polymer is reduced, and the environmental load reduction based on carbon neutral of carbon dioxide is reduced. The effect will not function sufficiently. Therefore, by setting the amount of the composite fiber used to 50% by mass or more, the three-dimensional knitted fabric in the present invention, and in turn, the mechanical properties of the civil engineering sheet of the present invention are maintained at a high level, and the effect of reducing the environmental load is maximized. It is possible to make it function. Thus, in using a biomass-derived polymer, by using a core-sheath composite fiber with a petroleum-based polymer, it is environmentally friendly and can compensate for disadvantages such as wear resistance that the biomass-derived polymer is inferior. Civil engineering sheets can be provided. Incidentally, fibers other than the composite fibers constituting the three-dimensional knitted fabric in the present invention are made of a polymer derived from petroleum.

  The petroleum-based polymer used in the present invention is not particularly limited as long as it can be melt-spun. Specifically, polyester represented by polyalkylene terephthalate such as polyethylene terephthalate (PET), polybutylene terephthalate, polytrimethylene terephthalate composed of petroleum-derived trimethylene glycol and terephthalic acid, nylon 6, nylon 66, nylon 46 Polyamides represented by nylon 11 and nylon 12, polyolefins represented by polypropylene and polyethylene, and polychlorinated polymers represented by polyvinyl chloride and polyvinylidene chloride. Examples thereof include fluorinated fibers such as polytetrafluoroethylene, copolymers thereof, and polyvinylidene fluoride. Of these, polyesters and polyamide polymers, which are preferably low cost, are preferable. More preferably, the biomass-based polymer has a large amount of aliphatic polyester-based polymer, so that a polyester-based polymer is preferable from the viewpoint of compatibility. Particularly preferred is polyethylene terephthalate in view of cost and handleability. In view of viscosity, thermal characteristics and compatibility, polyester polymers include aromatic dicarboxylic acids such as isophthalic acid and 5-sulfoisophthalic acid. Aliphatic dicarboxylic acids such as adipic acid, succinic acid, suberic acid, sebacic acid, dodecanedioic acid, and aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, Glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxypentanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid and other hydroxycarboxylic acids, and ε-caprolactone and other aliphatic lactones may be copolymerized.

  The biomass-derived polymer used in the present invention is not particularly limited as long as it can be melt-spun. Specifically, polylactic acid, polymers obtained by chemically polymerizing biomass monomers such as polytrimethylene terephthalate consisting of biomass-derived trimethylene glycol and terephthalic acid and polybutylene succinate, and polyhydroxyalkanoates such as polyhydroxybutyric acid And microbial production systems such as ate. Polylactic acid that is stable in heat resistance and has been relatively mass-produced is preferable.

  Examples of polylactic acid include poly D-lactic acid, poly L-lactic acid, poly D-lactic acid which is a copolymer of poly D-lactic acid and poly L-lactic acid, and a mixture of poly D-lactic acid and poly L-lactic acid (stereo Complex), a copolymer of poly D-lactic acid and hydroxycarboxylic acid, a copolymer of poly L-lactic acid and hydroxycarboxylic acid, poly D-lactic acid or poly L-lactic acid, aliphatic dicarboxylic acid and aliphatic diol Or a blend of these. As polylactic acid, as described above, L-lactic acid and D-lactic acid are used alone or in combination, and among them, the melting point is 120 ° C. or higher and the heat of fusion is 10 J / g. The above is preferable. The melting point of L-lactic acid and D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C., but in the case of a copolymer of D-lactic acid and L-lactic acid, the proportion of any component is about 10 mol%. Then, the melting point is about 130 ° C. Furthermore, when the proportion of any of the components is 18 mol% or more, the melting point is less than 120 ° C. and the heat of fusion is less than 10 J / g, which is almost completely amorphous. When such an amorphous polymer is used, it becomes difficult to heat-stretch particularly in the production process, and it becomes difficult to obtain high-strength fibers. Even if fibers are obtained, heat resistance and wear resistance It is not preferable because it becomes inferior to the above. Therefore, as polylactic acid, L / D or D / which is the content ratio (molar ratio) of L-lactic acid and D-lactic acid indicated by the content ratio of L-lactic acid or D-lactic acid when polymerizing using lactide as a raw material. L is preferably 82/18 or more, more preferably 90/10 or more, and even more preferably 95/5 or more. Among polylactic acids, a mixture (stereo complex) of poly D-lactic acid and poly L-lactic acid as described above is particularly preferable because it has a high melting point of 200 to 230 ° C. and is hardly affected by frictional heat.

  In the case of a copolymer of polylactic acid and hydroxycarboxylic acid, specific examples of hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxypentanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, etc. Can be mentioned. Of these, the use of hydroxycaproic acid or glycolic acid is preferable from the viewpoint of cost. In the case of a copolymer of polylactic acid, aliphatic dicarboxylic acid and aliphatic diol, the aliphatic dicarboxylic acid and aliphatic diol include sebacic acid, adipic acid, dodecanedioic acid, trimethylene glycol, 1,4-butane. Diol, 1,6-hexanediol, etc. are mentioned. Thus, when making polylactic acid copolymerize another component, it is preferable that polylactic acid shall be 80 mol% or more. If it is less than 80 mol%, the crystallinity of the copolymerized polylactic acid tends to be low, and the melting point is less than 120 ° C. and the heat of fusion is less than 10 J / g.

The molecular weight of polylactic acid is 1 to 100 (g / 10 min) as measured by a temperature of 210 ° C. and a load of 2160 g according to the ASTM D-1238 method used as an index of molecular weight. More preferably, it is 5-50 (g / 10min). By setting the melt flow rate within this range, strength, wet heat decomposability, and wear resistance are improved.
For the purpose of enhancing the durability of polylactic acid, a terminal blocking agent such as an aliphatic alcohol, a carbodiimide compound, an oxazoline compound, an oxazine compound, or an epoxy compound may be added to polylactic acid. Furthermore, as long as it does not impair the purpose of the present invention, a heat stabilizer, a crystal nucleating agent, a matting agent, a pigment, a light-proofing agent, a weathering agent, a lubricant, an antioxidant, an antibacterial agent are included in polylactic acid as necessary. Agents, fragrances, plasticizers, dyes, surfactants, flame retardants, surface modifiers, various inorganic and organic electrolytes, and other similar additives may be added.

  Moreover, the well-known additive which shows an effect as various fillers, a thickener, and a crystal nucleating agent can be added to a petroleum-based general-purpose polymer and a polymer whose core is derived from biomass as necessary. Specifically, carbon black, calcium carbonate, silicon oxide and silicate, zinc white, high-site clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide , Antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride, behenic acid amide and other aliphatic amide compounds, aliphatic urea compounds, benzylidene sorbitol compounds, crosslinked polymer polystyrene, rosin metal salts And glass fiber and whiskers. The substance may be added as it is, or may be added after necessary treatment as a nanocomposite. In order to achieve a good price and good physical property balance, an inorganic filler is preferably blended. Moreover, the compounding of a crystal nucleating agent is preferable.

  If necessary, colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, stabilizers such as antioxidants and UV absorbers, lubricants, mold release agents, and repellents. Water solution, antibacterial agent and other secondary additives can be blended.

  In the composition of the present invention, a plasticizer can be used in combination as long as the effects of the present invention are not impaired. By using a plasticizer, it is possible to reduce the melt viscosity during heat processing, especially during extrusion processing, and to suppress a decrease in molecular weight due to shearing heat generation, etc.In some cases, an improvement in crystallization speed can also be expected. Furthermore, when a film or sheet is obtained as a molded product, extensibility and the like can be imparted. Although there is no limitation in particular as a plasticizer, the following can be illustrated. As the plasticizer for the aliphatic polyester-based biodegradable polyester, ether-based plasticizers, ester-based plasticizers, phthalic acid-based plasticizers, phosphorus-based plasticizers and the like are preferable. Agents and ester plasticizers are more preferred. Examples of ether plasticizers include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of ester plasticizers include esters of aliphatic dicarboxylic acids and aliphatic alcohols.

  In addition, the conjugate fiber in the present invention is preferably a concentric core-sheath type conjugate fiber in which the core portion and the sheath portion are arranged substantially concentrically. By setting it as such a structure, the effect which distributes a general purpose polymer uniformly to a sheath part can be show | played. If the core component is present eccentrically, a thin portion is formed in the general-purpose polymer layer of the sheath, and in the portion where the general-purpose polymer layer is thin, wear resistance may be deteriorated due to aging or severe use, which is not preferable. .

  The thickness of the civil engineering sheet of the present invention is preferably 10 mm or more, and more preferably 20 mm or more. When the thickness is less than 10 mm, the amount of drainage is not sufficient when used as a drainage sheet, and there is a possibility that the depth for filling earth and sand cannot be sufficiently obtained when used for erosion prevention. It is not preferable.

The mass of the civil engineering sheet of the present invention is preferably 500 to 3000 g / m2. When the mass is less than 500 g / m ² , the mechanical properties of the sheet itself tend to be low, which is not preferable. On the other hand, when the mass is heavier than 3000 g / m ² , it becomes difficult to fill with earth and sand when used for preventing erosion, and not only is transportation inconvenient in other applications, but also the workability is impaired. This tends to be unfavorable.

  Furthermore, as a civil engineering sheet of the present invention, it is possible to harden the knitted structure by heat fusion yarn or resin processing for the purpose of imparting dimensional stability, adjusting the required texture, and preventing monofilament scattering that occurs during sheet cutting. it can. In this case, the amount of heat-sealing yarn used is preferably 3 to 20% by mass. When the amount used is less than 3% by mass, sufficient adhesiveness tends to be not ensured. In addition, there is a possibility that inconvenience may occur in terms of workability such as occurrence of troubles during construction due to elongation due to its own weight or the like. For this, when 3% by mass or more of the heat-sealing yarn is used, it becomes part of the knitted structure by heat-sealing, and other composite fibers can be firmly fixed. It is not necessary to add a large amount, and too much is not preferable because it deviates from the gist of the present invention. Here, the heat-sealable fiber that can be used is not particularly limited as long as the fiber has a compound having a melting point lower than that of the fiber constituting the sheet of the present invention. In consideration of adhesiveness and the like, the fiber of the same resin series as that of the sheet constituent fiber is most preferable, and there are those composed of a single component and those composed of a plurality of components.

  The civil engineering sheet of the present invention can be subjected to resin processing. In this case, the resin application amount is preferably 1 to 100% omf (indicating a ratio to the weight of on the mass of fabrics). If the resin application amount is less than 1% omf, the effect is not sufficiently exhibited. Conversely, if the application amount is more than 100% omf, not only does the weight of the sheet become heavy and the workability becomes difficult, but also the space of the three-dimensional knitted fabric This is not preferable because it may remain as a lump in the part and hinder the achievement of the required performance.

  Here, the resin used for the resin processing is not particularly limited, and can be arbitrarily selected according to the purpose. Specific examples include ester resins, amide resins, phenol resins, acrylic resins, urethane resins, silicone resins, imide resins, various rubber resins, and chlorinated resins. The same resin system as the resin system of the fibers constituting the present invention is preferable from the viewpoints of interface adhesiveness, separation at the time of disposal, and the like.

  The production method of the composite fiber and the three-dimensional knitted fabric in the present invention is not particularly limited, and can be performed by a conventional method.

Next, the present invention will be described in detail. In addition, the measuring method and evaluation method of each physical property value in an Example are as follows.
(1) Melting point (° C.) and heat of fusion (J / g) of polylactic acid: Using a differential scanning calorimeter DSC-2 manufactured by PerkinElmer, Inc. It was measured.
(2) Content ratio (molar ratio) of L-lactic acid and D-lactic acid in polylactic acid: High-performance liquid chromatography (HPLC) method using an equal mass mixed solution of ultrapure water and 1N sodium hydroxide in methanol as a solvent. It was measured by. Sumichiral OA6100 was used for the column, and it detected with the UV absorption measuring device.
(3) Fiber fineness (dtex): Measured according to JIS L-10153 positive fineness.
(4) Strength (fiber) (cN / dtex): Measured according to JIS L-1013 standard time test for tensile strength and elongation.
(5) Abrasion resistance: Based on JIS-L1021, a sag measurement test was performed after stepping 10,000 times with a load of 1 kg using a dynamic load fatigue tester, and the appearance change was observed.
(6) Dimensional stability: A sheet having a width of 1.0 m and a length of 2.0 m was lifted to 2.0 m or more in the length direction, and elongation due to the weight of the sheet was confirmed. A case where the elongation (%) was 15% or less was regarded as acceptable.

(Example 1)
Polylactic acid having a melting point of 170 ° C., heat of fusion of 38 J / g, L / D of 98.5 / 1.5, which is the content ratio of L-lactic acid and D-lactic acid, and aromatic polyester having a melting point of 217 ° C. Each of the chips was dried under reduced pressure using PET copolymerized with 15 mol% of isophthalic acid and then supplied to a concentric MF core-sheath type composite melt spinning apparatus to perform melt spinning. At this time, the copolymer PET was arranged so as to be a sheath part and polylactic acid was a core part, the composite ratio (mass ratio) was 50/50, and melt spinning was performed at a spinning temperature of 240 ° C. The obtained composite fiber had a round cross-sectional shape with a fineness of 330 dtex1 filament and 1100 dtex1 filament, a tensile strength of 4.0 cN / dtex, and a cut elongation of 31.9%.

Using a warp knitting machine with a 6-gauge double-row needle bed with an improved knitting element capable of knitting rigid monofilaments, upper and lower structures are constructed in the L1, L2, L5 and L6 ridges using the chain links in Table 1 330 dtex1 filament to be supplied, 1100 dtex1 filament to be connected yarn is supplied to L3 and L4, and a hexagonal integrated three-dimensional material whose upper and lower surfaces are composed of four courses on one side is knitted, and then the form is arranged Therefore, the draw-out was set at 120 ° C. for 2 minutes so that the hexagonal structures on the upper and lower surfaces were almost regular hexagons, and the civil engineering sheet of Example 1 having a thickness of 30 mm and a mass of 1670 g / m ² was obtained. .

(Example 2)
The civil engineering sheet obtained in Example 1 was dipped with an acrylic emulsion (Boncoat AC-231: Dainippon Ink & Chemicals, Inc.), dried at 120 ° C. for 2 minutes, and the resin adhesion was 15% omf. A civil engineering sheet of Example 2 having a thickness of 30 mm and a mass of 1920 g / m ² was obtained.

(Example 3)
Using the composite fiber obtained in Example 1, 330 dtex1 filaments were used for L1, L2, and L5 に よ る by the chain links in Table 2, and Melset <4080> 280 dtex24 filaments (manufactured by Unitika Fiber Co., Ltd., core sheath) were used for L6. Heat-bonding binder fiber (melting point 110 ° C.) and 330 dtex1 filament are supplied to form upper and lower structures, and L3 and L4 are supplied with 1100 dtex1 filaments as connecting yarns, and the upper and lower surfaces are hexagonal shape consisting of 4 courses on one side In order to arrange the shape of the three-dimensional material, and then the shape of the hexagonal structure on the upper and lower surfaces is almost regular hexagonal to set the shape, set the heat spreader at 120 ° C. × 2 minutes, and set the thickness to 30 mm. The civil engineering sheet of Example 3 having a mass of 1680 g / m ² was obtained.

(Comparative Example 1)
Polylactic acid having a melting point of 170 ° C., a heat of fusion of 38 J / g, and a content ratio of L-lactic acid to D-lactic acid of 98.5 / 1.5 was dried under reduced pressure and then put into a melt spinning apparatus. The melt spinning was carried out at a spinning temperature of 240 ° C. The obtained polylactic acid fiber for upper and lower tissues had a round cross-sectional shape with a fineness of 220 dtex48 filament, a tensile strength of 4.5 cN / dtex, and a cut elongation of 30.4%. Further, the polylactic acid was melt-spun under the same conditions as above using a concentric MF core-sheath composite spinning device to obtain a monofilament of 1100 dtex 1 filament for connecting yarn. The obtained monofilament had a round cross-sectional shape, the tensile strength was 3.7 cN / dtex, and the cut elongation was 30.1%. Next, a three-dimensional structure was produced using each of the obtained fibers in the same manner as in Example 1 to obtain a civil engineering sheet of Comparative Example 1 having a thickness of 30 mm and a mass of 1580 g / m ² .

(Comparative Example 2)
As an aromatic polyester, PET copolymerized with 15 mol% of isophthalic acid having a melting point of 217 ° C. was dried under reduced pressure, and then supplied to a melt spinning apparatus to perform melt spinning at a spinning temperature of 240 ° C. The obtained polyester fiber for upper and lower tissues had a round cross-sectional shape with a fineness of 220 dtex48 filament, a tensile strength of 4.7 cN / dtex, and a cut elongation of 30.2%. In addition, using the concentric MF core-sheath composite spinning device, the above PET copolymer was melt-spun under the same conditions as above, and a 220 dtex 1 filament monofilament was obtained. The obtained monofilament for connecting yarn had a round cross-sectional shape, the tensile strength was 3.9 cN / dtex, and the cut elongation was 24.1%. Next, using the obtained fiber, a three-dimensional structure was produced in the same manner as in Example 1, and a sheet of Comparative Example 2 having a thickness of 25 mm and a mass of 1250 g / m ² was obtained.

(Comparative Example 3)
Polylactic acid having a melting point of 170 ° C., heat of fusion of 38 J / g, L / D of 98.5 / 1.5, which is the content ratio of L-lactic acid and D-lactic acid, and aromatic polyester having a melting point of 217 ° C. Each of the chips was dried under reduced pressure using PET copolymerized with 15 mol% of isophthalic acid and then supplied to a concentric MF core-sheath type composite melt spinning apparatus to perform melt spinning. At this time, the copolymer PET was arranged so as to be a sheath part and polylactic acid was a core part, the composite ratio (mass ratio) was 50/50, and melt spinning was performed at a spinning temperature of 240 ° C. The obtained conjugate fiber for connecting yarn had a round cross-sectional shape with a fineness of 110 dtex1 filament, a tensile strength of 4.1 cN / dtex, and a cut elongation of 30.7%.

Next, in the same manner as in Example 3, 330 dtex1 filaments were supplied to L1, L2, and L5 に よ る by the chain links in Table 2, and Melset <4080> 280 dtex24 filaments and 330 dtex1 filaments were supplied to L6 to form upper and lower tissues. L3 and L4 are fed with 110 dtex1 filaments as connecting yarns to knitted a hexagonal integrated three-dimensional material with four sides on the upper and lower sides, and then 6 on the upper and lower sides to adjust the form. The draw-out was set at 120 ° C for 2 minutes so that the square structure was almost a regular hexagon, but the pile yarn did not stand upright and the thickness became 20 mm, and the pile yarn was curved. The civil engineering sheet of Comparative Example 3 having a mass of 890 g / m ² was obtained.

(Comparative Example 4)
Polylactic acid having a melting point of 170 ° C., heat of fusion of 38 J / g, L / D of 98.5 / 1.5, which is the content ratio of L-lactic acid and D-lactic acid, and aromatic polyester having a melting point of 217 ° C. Each of the chips was dried under reduced pressure using PET copolymerized with 15 mol% of isophthalic acid and then supplied to a concentric MF core-sheath type composite melt spinning apparatus to perform melt spinning. At this time, the copolymer PET was arranged so as to be a sheath part and polylactic acid was a core part, the composite ratio (mass ratio) was 50/50, and melt spinning was performed at a spinning temperature of 240 ° C. The obtained composite fiber had a round cross-sectional shape with a fineness of 330 dtex 1 filament and 3550 dtex 1 filament, a tensile strength of 4.0 cN / dtex, and a cut elongation of 30.7%.

  Next, in the same manner as in Example 3, 330 dtex1 filaments were supplied to L1, L2, and L5 に よ る by the chain links in Table 2, and Melset <4080> 280 dtex24 filaments and 330 dtex1 filaments were supplied to L6 to form upper and lower tissues. L3 and L4 were fed with 3550 dtex1 filaments as connecting yarns and knitted a hexagonal integrated three-dimensional material consisting of 4 courses on each side, but needle breakage occurred frequently during knitting, Knitting was impossible.

  Table 2 shows the results for the sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 4. In Examples 1, 2, and 3, the use amount of the core-sheath composite fiber was appropriate, and the appearance and the abrasion resistance were satisfactory. In addition, both of the dimensional stability values are acceptable, but in Examples 2 and 3, since resin processing or use of heat-sealing yarn is used, the elongation is a low value of 2%, which is more excellent. Dimensional stability was ensured. On the other hand, in Comparative Example 1, since it is a sheet formed only from polylactic acid fibers without containing composite fibers, the abrasion resistance was poor and many fluffs were generated. In Comparative Example 2, since the sheet is made of only aromatic polyester and does not contain a polymer derived from biomass, the wear resistance is good, but it is a problem in terms of reducing environmental load based on carbon neutral. It was. Further, in Comparative Example 3, since the fineness of the connecting yarn was as low as 110 dtex, there were difficulties in the three-dimensional shape of the three-dimensional knitted fabric, and there were some parts that were partially broken during the test in terms of wear resistance. It was. On the other hand, in Comparative Example 4, since the fineness of the connecting yarn was too large, needle breakage occurred frequently during knitting, and knitting was impossible.

Claims (6)

A civil engineering sheet formed by a three-dimensional knitted fabric, wherein at least 50 mass% or more of the fibers constituting the three-dimensional knitted fabric have a core-sheath shape in cross section, and the sheath portion is a petroleum-based general-purpose polymer. A civil engineering sheet, characterized in that it is a composite fiber that is formed and has a core formed of a polymer derived from biomass. The civil engineering sheet according to claim 1, wherein the sheath is formed of polyethylene terephthalate. The civil engineering sheet according to claim 1 or 2, wherein the core is made of polylactic acid. A monofilament connecting yarn is 220~3330dtex in the three-dimensional knit fabric, civil engineering sheet thickness in the sheet is 10mm or more, and the mass according to any one of claims 1 to 3, characterized in that the 500~3000g / ^{m 2} . The civil engineering sheet according to any one of claims 1 to 4, wherein 3 to 20% by mass of heat-sealing yarn is used. The civil engineering sheet according to any one of claims 1 to 5, wherein the sheet is processed with a resin at 1 to 100% omf.